This law legalizes the possession of marijuana for adults age 21 and older. The only marijuana that would be legal to sell in this state would be grown by specially-licensed Washington farmers and sold in standalone, marijuana-only stores operated by private Washington businesses licensed and regulated by the state. There would be a 25% sales tax, with 40% of the new revenues going to the state general fund and local budgets, and the remainder dedicated to substance-abuse prevention, research, education and health care. Advertising would be restricted. A new marijuana DUI standard that operates like the alcohol DUI standard would be established.

Here's how Initiative 502 will be described on your November 6 general election ballot:

This measure would license and regulate marijuana production, distribution, and possession for persons over twenty-one; remove state-law criminal and civil penalties for activities that it authorizes; tax marijuana sales; and earmark marijuana-related revenues.

And here's the summary we were required to print on signature petitions to put Initiative 502 on this year's ballot:

This measure would remove state-law prohibitions against producing, processing, and selling marijuana, subject to licensing and regulation by the liquor control board; allow limited possession of marijuana by persons aged twenty-one and over; and impose 25% excise taxes on wholesale and retail sales of marijuana, earmarking revenue for purposes that include substance-abuse prevention, research, education, and healthcare. Laws prohibiting driving under the influence would be amended to include maximum thresholds for THC blood concentration.

Thank you for breaking that down Daniel. I am curious though about the THC blood concentration level seems like it could get us into trouble. If I smoke a lot of herb (like usual) i could have not smoked before I got pulled over but my THC level might be high(haha), because I smoked a lot the night before or ate a brownie. There needs to be a way to regulate how high you are at that moment. Not what is in your blood stream. Makes working out and sweating out THC even more importand IMO. Am I understanding this right?

This appears to be the operative text. As with any DUI, the law enforcement officer must have "reasonable grounds" to
believe the person has been driving under the influence.

Quote(c) If the driver submits to the test and the test is administered, the driver's license, permit, or privilege to drive will be suspended, revoked, or denied for at least ninety days if:
(i) The driver is age twenty-one or over and the test indicates either that the alcohol concentration of the driver's breath or blood
is 0.08 or more, or that the THC concentration of the driver's blood is 5.00 or more;

I'll leave it to someone else to chime in as to what it would take to get one's THC concentration up to (or down to) 5.00....

What are the odds that this law will stand up in court? Seems unlikely to me the feds will actually let a state sell legal marijuana, which is still illegal under federal law (see: all the issues with medical marijuana's legality)

Hopefully within a year they will develop a mouth swab test you can purchase yourself at head shops to test yourself. That is my hope, at least... I'm all for driving 'responsibly' if the tools to do so are actually available.